It looks like puppetlabs/concat is switching to using a second module (electrical/file_concat). Now I have to update my .fixtures.yml (which is fine, I do want to know about dependency changes), but there isn’t a released version of puppetlabs/concat with electrical/file_concat yet.

TL;DR
All of the rspec testing in the world won’t help if dependencies are unstable. Puppet module git repository master branch should at all times be the same as the code released to the Forge.